1. Field of the Invention
The present invention relates to converting analog medical video data to a digital object that associates descriptive data with the video, and, in particular, to forming Digital Imaging and Communications in Medicine (DICOM) objects from analog medical video data in a legacy data collection system.
2. Description of the Related Art
Medical care facilities collect video data in association with diagnostic and interventional radiological procedures, including fluorescence images of relative transmission and computer aided tomography (CAT) scan images based on Roentgen rays (X-rays), and echograms based on ultrasound. To associate each video clip with the patient and procedure for which the images were collected, characters were included in the recorded images that identified the patient-imaging session combination (called herein a patient-session identifier). Thus a human viewer of the video, such as a doctor could be assured that a particular video being viewed applied to a particular case under consideration.
Also associated with the video data is other information about the imaging session on the patient, such as the patient name or other identifier, the patient demographic data, e.g., age, height, weight, vital signs, family history, personal history, the imaging system identifier and maintenance history, the procedure itself, including study data when the imaging was performed as part of a study. This other descriptive data is stored separately from the video. For example, the non-video descriptive data was stored in journal entries or forms in a paper record, but more often as binary data on a computer storage medium in various files, sometimes within a database system.
These video data are archived as a record of the procedure, as a record of the patient's condition at the time of the procedure, and a baseline of patient condition to monitor the progression of a disease or a healing treatment. Several minutes to hours of such data is collected at a single medical facility for each of hundreds to thousands of patients per year, for many years.
In the past, the most efficient storage for such data has been as analog video data. Digital storage would require many terabytes of storage (a byte is about eight binary digits, called bits, a megabyte is a million bytes, and a terabyte is 1012 bytes—a million megabytes). Media such as hard magnetic disks for such data had limited capacity and were expensive. Vast numbers of such disks were required for digital storage. Analog formats could store more hours of data per medium and more cheaply. Many different such formats have been utilized from Beta-format video tapes, to standard VHS format video stapes, to proprietary formats defined for particular data collection systems. The analog data drives a television display using one of several worldwide standards, including PAL in Europe and NTSC in the United States. Several patient-session video clips are stored on a particular medium, typically a video tape, and the media are collected in libraries held at or for the benefit of each medical facility.
A variety of legacy and emerging systems have been used to collect video imaging data for patients, including, among others, systems from MERGE HEALTHCARE™ of Milwaukee, Wis.; Impax Master Patient Index (MPI) of AGFA HEALTHCARE™ of Mortsel, Belgium; Horizon Cardiology Echo of MCKESSON ALIPORT™ of Alpharetta, Ga.; Radiance Picture Archiving and Communication Systems (PACS) DEJARNETTE RESEARCH SYSTEMS, INC.™, of Towson, Md.; NAI DiCOM box CA+ Cine to DICOM of AMPRONIX INCORPORATED™, Irvine, Calif.; PACS systems of VEPRO™ of Hahn, Germany; CapturePRO systems of PEGASUS IMAGING CORPORATION™ of Tampa, Fla.; and Video Acquisition Workstation (VAW) of RAYPAX™ of Seoul, Korea.
When an archived video is to be reviewed for any reason, the appropriate volume of the medium must be identified, typically in a list or digital database, retrieved from the library, which can take several minutes if stored on site to several days if stored off site. Furthermore, a suitable player must be identified and located, the medium volume must be inserted, and the tape played forward until the correct clip is positioned in the viewer. There are costs associated with all these steps, not the least of which is the doctor's time in waiting for the appropriate clip to be positioned in the player after the data is requested. A significant cost to the patient's health and the doctor's inefficiency is the delay from the time that a need for the clip is identified until the proper medium volume is provided. Other costs include the librarian's salary, the salary of any other operators or technicians involved, the storage space for the media, the transportation costs between library and viewer, and the cost of maintaining the viewer, sometimes different viewers for different imaging systems. Such costs can often exceed a hundred thousand dollars a year.
Current digital storage techniques, such as hard magnetic drives and optical media such as DVDs, are now capable of efficiently storing such volumes of video data. An advantage of digital storage is that digital video data can now be stored in association with patient and procedure data related to the video data on the same storage medium. Data structures that combine multimedia data, images, sound, video, character and numeric data have been developed. Some are flexible enough to define their own fields. Object-oriented data bases define data objects that include not only data of different types, but also methods that are used for receiving input data, storing it, and retrieving it on request.
An object-oriented data format that has been adopted at many medical facilities is the Digital Imaging and Communications in Medicine (DICOM) system. DICOM is well known and widely used in the art of medical data and is available from the National Electrical Manufacturers Association (NEMA) of Rossyln, Va. Documentation of the DICOM standards is available at the time of this writing at subdomain dicom at domain nema at top level domain org as a Hypertext Markup Language (HTML) document ps3set.cfm in directory stds. The entire contents of ps3set.cfm are hereby incorporated by reference as if fully set forth herein.
There are benefits to converting the analog medical video data to digital data for storage in digital objects in association with other patient and procedure data, such as in DICOM objects. For example, the video and associated descriptive data can be retrieved over a network as soon as a need for it is identified, without intervention or costs of a human librarian or transporter, or the costs of one or more legacy analog video players, or the cost of time to advance a video tape. High capacity network digital storage is all that is required, and that is available reliably and cheaply as a commodity in current markets. The data can be kept indefinitely in a retrievable form independent of video players, even for the lifetime of a patient (many decades).
Unfortunately there are substantial obstacles in converting the analog data to digital form. Current systems involve a human operator playing each tape, determining the beginning and end of a clip associated with a single patient-imaging session, visually identifying the particular patient-imaging session based on the characters shown on the image, and retrieving data related to that patient-imaging session from one or more other digital files or databases. Then the portion of the tape must be played through an analog to digital converter and stored with the data from the database. Each legacy system would consume tens of thousands of hours of operator time (years of salary) to process all the video clips. Also, because the work is tedious and not related to a particular critical need of the patient whose data is being converted, the operator is prone to lose attention and to generate errors. Therefore the costs of the errors or checks to catch and correct errors would also be incurred. Again, these conversion costs can be expected to exceed a hundred thousand dollars a year for several years.
Based on the foregoing description, there is a clear need for techniques to convert large amounts of analog medical video data to digital objects that do not suffer the disadvantages of prior approaches. In particular, there is a need for techniques to convert analog medical video data to digital objects that involve very little human involvement.
The past approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not to be considered prior art to the claims in this application merely due to the presence of these approaches in this background section.